Shielded housing for holding electronic components, particularly electronic air bag control devices

ABSTRACT

The invention relates to a housing for an electronics unit, especially for an airbag control device, whereby at least the metal walls of the housing are provided with a moisture repellent coating. The inventive housing is made of bent and interconnecting sheet metal elements which are extrusion-coated with plastic on at least one side.

BACKGROUND OF THE INVENTION

The subject invention is directed toward the art of electronic componenthousings and, more particularly, to electronic air bag control housingshaving electromagnetic shielding metal walls provided with a moisturerepellant coating. The invention is especially well suited for use withelectronic air bag control devices and will be described with particularreference thereto; however, the invention is capable of a broaderapplication and can be used for a variety of purposes in manyenvironments.

Cast aluminum housings provided with threaded sheet metal covers havebeen used in the past including use in connection with air bag controldevices. One disadvantage of cast aluminum housings, however, is thatthey offer almost no protection from moisture intrusion. For thatreason, the electronics contained within the cast aluminum housings mustbe protected from moisture using any suitable means such as by immersionof the electronic components in an appropriate moisture repellentliquid.

Housings formed in accordance with the above prior art teachings havemany drawbacks including poor electromagnetic shielding. In addition,after the printed circuit boards or other electronic components areimmersed in the moisture repellent coating, repair of the electronicsbecomes impossible. Moreover, following the immersion step, thereremains the possibility of the unwanted presence of moisture on theprinted circuit board remains.

There is, therefore, the need for an electronic components housing ofthe type described above that is less sensitive to moisture and providesgood electromagnetic shielding while also enabling repair of theelectronics as necessary.

SUMMARY OF THE INVENTION

The subject invention provides an electronic components housing whichprovides good electromagnetic shielding, electronic component repairfriendliness, and an improved moisture sensitivity. The subject housingincludes a pair of bent and interconnected sheet metal elements, whichare extrusion-coated at least on one side or surface thereof with aplastic covering. A bent sheet metal housing is employed according tothe invention, which is subsequently extrusion-coated on one or bothsides with a plastic moisture repellent covering. As a beneficialresult, the housing is made water-tight. Preferably, the bent andinterconnected sheet metal elements are substantially non-flexible. Inthat regard, any suitable substantially rigid load supporting sheetmetal can be used. By means of extrusion coating the sheet metalcomponents with plastic, it is possible to realize a wide range offunctional elements in the housing including retention rails forimpervious surfaces.

The housing according to the preferred embodiment of the invention isfurther advantageous in that the most favorable material and/or the mostfavorable material combination(s) is/are employed for use in theelectromagnetic shielding. Preferably, a selectively insertable plug isused in combination with the housing to realize an absolutelywater-tight effect. Accordingly, pre-emersion of the printed circuitboard into a suitable water repellent liquid is not required. Thisresults in the cost benefit of a reduction in the manufacturing effortsand steps required to construct the housing.

In accordance with a further aspect of the invention, ventilation of thehousing is provided using a ventilation membrane.

In accordance with a yet further aspect of the invention, occluded airvolume is minimized by suitably shaping the plastic material extrudedonto the sheet metal component.

Still a further aspect of the invention is that subsequent repair of theelectronic components within the housing remains available.

A primary object of the invention is the provision of an electroniccomponent housing of the type described which includes one or moresubstantially non-flexible bent and interconnected sheet metal elementswhich are extrusion-coated on at least one side with a moisturerepellent covering of a plastic material.

Yet another object of the invention is the provision of an electroniccomponent housing which enables a printed circuit board or the like tobe contained therein in a water-tight state without the need forpre-emersion of the printed circuit board in a water repellent liquid.

Still other advantages and benefits of the invention will becomeapparent to those of skilled in the art upon a reading and understandingof the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangementsof parts, a preferred embodiment of which will be described in detail inthis specification and illustrated in the accompanying drawings whichform a part hereof, and wherein:

FIG. 1 is a schematic side lateral view illustrating the sheet metalelements of the housing in an interconnected arrangement;

FIG. 2 is a perspective view of the housing shown in FIG. 1;

FIG. 3 is a top plan view of the housing illustrated in FIGS. 1 and 2;

FIG. 4 is a cross-sectional view taken along line IV—IV of FIG. 3; and,

FIG. 5 is a cross-sectional view taken along line V—V of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings wherein the showings are for the purposesof illustrating the preferred embodiment of the invention only and notfor purposes of limiting same, FIGS. 3-5 show the overall arrangement ofa housing 1 formed in accordance with the present invention forcontaining electronic components, particularly electronic air bagcontrol units. The housing 1 includes bent and interconnected sheetmetal elements 2 and 3, which are extrusion-coated on at least one sideor surface thereof with a moisture repellent covering of a plasticmaterial 4. The sheet metal elements are preferably substantiallynon-flexible and capable of supporting electronic printed circuitboards, their mountings, and the like. In the arrangement illustrated,the housing and sheet metal elements are shaped from a plate bar.

FIGS. 1 and 2 illustrate the sheet metal elements 2 and 3 without theouter plastic coating and consisting of a housing upper part 20 and abottom plate 30. The housing upper part 20 is formed into a shapeincluding an upper cover plate and three side walls.

As shown in FIG. 2, the upper housing part 20 and the bottom plate 30are provided with a plurality of spaced apart recesses 10 and 10′,respectively, for embedding the extruded plastic material 4 (FIGS. 4 and5). The plurality of recesses are adapted to receive and hold theextruded plastic material in place relative to the upper part 20 and thebottom plate 30. Preferably, the plurality of recesses are arranged onthe upper housing part and the bottom plate in a continuous array orpattern as illustrated.

With continued reference to FIG. 2, the housing illustrated includes oneor more areas free from plastic material on inside areas and/or outsideareas of the housing which preferably function as retention rails or thelike.

As is apparent from FIGS. 1 and 5, a dome 5 is formed by at least one ofthe sheet metal elements 2 or 3, preferably, however, the dome is formedon the bottom plate 30. In the embodiment illustrated, the dome 5 isprovided in the bottom plate 30 for installation of a suitable groundingscrew 8 in the housing 1 such as illustrated in FIG. 5.

With continued reference to FIGS. 1 and 5, at least one side wall 14 ofthe housing upper part is adapted for connection with a bushing 9. Agrounding screw 8 is selectively inserted into the dome 5 and thebushing 9.

As illustrated in FIGS. 2 and 3, the bottom plate 30 of the housingincludes at least one attachment opening. Preferably, however, threeattachment openings 12 are provided. The upper right hand representationof the attachment opening 12 illustrated in FIGS. 3 and 4 illustrates aplurality of creases 32 formed around the attachment opening.Preferably, the creases 32 are arranged in a star-shape pattern. Thecreases present raised portions which penetrate oxide layers which maypotentially form on mounting hardware (not shown) to thereby guarantee asafe electrical grounding connecting using the “toothed disk” technique.

It is to be noted that in accordance with the present invention, themoisture repellent covering of a plastic material can be selectivelyapplied to one or both sides or surfaces of the bent and interconnectedsheet metal elements. It is, however, essential that the front side ofthe attachment opening 12 and the creases 32 remain free from plasticcoating covering so that a good electrical grounding connection with thehousing can be made between the housing and other associated electricalcomponents.

With reference now to FIG. 5, a printed circuit board 15 is illustratedwithin the housing 1. At least one electrically conductive connection isprovided between the housing 1 and the printed circuit board 15. Asshown, the at least one electrically conductive connection is formed bymeans of a plastic free retention rail 25 shown best in FIG. 1. It is tobe appreciated, however, that the electrically conductive connection canalso be formed as a spring contact, a screw connection, or anycombination thereof. Moreover, as shown in FIG. 5, a plug 17 isselectively positioned in contact with the printed circuit board 15. Theplug 17 is selectively at least partially arranged within the housing 1.

A ventilation membrane 28 is illustrated in FIG. 4. The ventilationmembrane 28 is preferably arranged inside the housing by means of whichventilation of the housing is effected in a simple manner. Theventilation membrane covers a ventilation opening suitably provided inthe housing. The membrane is connected to the housing using glue or thelike or through a mechanical connection such as pressing the membraneinto the opening.

It is to be appreciated that by extrusion-coating one or both surfacesof the sheet metal elements 2 and 3 of the housing, together with thefeature of the plug 17, that the housing is made absolutely water-tight.One benefit flowing from this is that emersion of the printed circuitboard 15 into a water repellent liquid is no longer required.Accordingly, the printed circuit board remains readily accessible sothat subsequent repairs thereto are possible. In addition, the housingprovides excellent electromagnetic shielding to electronic componentscontained therein. Lastly, as is evident from the drawings and thedescriptions above, the housing is simple and inexpensive tomanufacture.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon a reading and understanding of this specification. It isintended to include all such modifications and alterations insofar asthey come within the scope of the appended claims or the equivalentsthereof.

What is claimed is:
 1. A water-tight electronic component housing foruse with an airbag control device, the housing comprising: a pair ofbent and interconnected sheet metal elements comprising a housing upperplate and a bottom plate, said upper plate and bottom plate eachincluding a plurality of recesses adapted to receive a moisturerepellant covering of a plastic material across a surface of each plate,said plastic material being extrusion-coated on at least one side ofsaid upper plate and said bottom plate to form a water-tight seal. 2.The housing according to claim 1, wherein the pair of sheet metalelements are extrusion-coated with said plastic material on both sides.3. The housing according to claim 2, wherein the sheet metal elementsare shaped from a single plate bar.
 4. The housing according to claim 1,wherein said plurality of recesses are arranged in a substantiallycontinuous pattern in at least one of the housing upper part and thebottom plate.
 5. The housing according to claim 3 wherein at least oneof the sheet metal elements includes a plastic-free retention area on aone of an inside surface and an outside surface.
 6. The housingaccording to claim 1 further including: at least one dome area providedon at least one sheet metal element.
 7. The housing according to claim6, wherein: said dome area is formed in the bottom plate for insertionof an associated grounding screw in the housing.
 8. The housingaccording to claim 6 further including a side wall provided with asleeve adapted to fasten with said associated grounding screw.
 9. Thehousing according to claim 1 wherein the bottom plate further includesat least one attachment opening.
 10. The housing according to claim 9,further including at least one crease formed around the attachmentopening.
 11. The housing according to claim 10 further including aprinted circuit board disposed within said housing, at least oneelectrically conductive connection of the printed circuit board beingelectrically connected with the housing.
 12. The housing according toclaim 11, wherein the electrically conductive connection includes atleast one of a retention rail, a spring contact, and a screw connection.13. The housing according to claim 11, further including a plugconnected with the printed circuit board, the plug being at leastpartially arranged in housing.
 14. An electronic component housing foruse with an airbag control device, comprising: a housing upper plate anda housing lower plate each comprising a plurality of recesses extendingacross said upper and lower plates; a moisture-repellant materialextrusion-coated onto at least one side of said upper and lower plates,said moisture-repellant material being received within said recesses;and, a ventilation membrane arranged in the housing interior disposedbetween said upper plate and said lower plate.
 15. The housing accordingto claim 14 further including: at least one dome area provided on atleast one sheet metal element.
 16. The housing according to claim 15,wherein: said dome area is formed in the bottom plate for insertion ofan associated grounding screw in the housing.
 17. The housing accordingto claim 15 further including a side wall provided with a sleeve adaptedto fasten with said associated grounding screw.
 18. The housingaccording to claim 14 wherein the bottom plate further includes at leastone attachment opening.
 19. The housing according to claim 18, furtherincluding at least one crease formed around the attachment opening. 20.The housing according to claim 19 further including a printed circuitboard disposed within said housing, at least one electrically conductiveconnection of the printed circuit board being electrically connectedwith the housing.